1. Field
Aspects of the present invention relate to a secondary battery, which can reduce or prevent an uncoated portion and the rest of an electrode assembly from being damaged when the uncoated portion of the electrode assembly is coupled to a collector plate by laser welding.
2. Description of the Related Art
Generally, a secondary battery refers to a battery that may be charged and discharged, unlike a primary battery, which is not designed to be recharged. Small secondary batteries are widely used (utilized) in advanced electronic equipment, e.g., portable phones, notebook computers and camcorders. Large secondary batteries are widely used for, e.g., driving the motors of electric cars and the motors of hybrid cars. The secondary battery is generally configured such that an electrode assembly is provided within a case, and an electrode terminal is coupled or connected to the electrode assembly through a collector plate welded to the electrode assembly.
Particularly, an uncoated portion of an electrode assembly and a collector plate of a secondary battery are coupled to each other by welding, and welding quality is quite an important factor in determining electrical characteristics of the secondary battery. Accordingly, it is desirable to develop a reliable welding process.